Destruction of volumes of tissue in the human body is desired in many situations. Such is the case with the most common problem of expanded male prostate, and the case of benign and malignant tumors in the liver, breast or brain. And such is the case of the uterine layer (endometrium) of excessively bleeding women.
Excessive and/or prolonged menstrual bleeding (or chronic menorrhagia), is commonly treated by birth control pills, other hormonal therapies, or by a minor operation called "D and C" (dilation and curettage) involving a scraping of the lining of the uterus. When such treatments are not effective, a hysterectomy is generally performed which involves removing the uterus and the lining along with it. Approximately 600,000 hysterectomies are performed in the USA each year.
One method of tissue destruction is known as interstitial thermo-therapy (ITT). In this method, the tissue temperature is elevated (above a certain threshold temperature for a certain duration) by absorption of (laser) light. Light, in turn, is transmitted to the scene via an optical fiber and is scattered and diffused to be absorbed by the volume of tissue to be destroyed. Usually, the light source is a laser, such as a Nd:YAG laser system or Diode laser system.
Recently, a technique has been developed using laser energy to ablate the uterine lining such as to cause scarring that prevents the lining from growing back. In this technique, a laser beam is conducted in the uterus by means of an optical fiber. The optical fiber is inserted via a channel of a hysteroscope, enabling the physician to view the interior of the uterus as the physician manipulates the tip of the optical fiber. The physician sweeps the tip of the optical fiber across the uterine lining to ablate the lining to a depth of about 3-5 mm. This procedure is carried out under general anesthesia by a skilled operator, is time consuming and there is a risk of uterine perforation.
An alternative technique is to slowly elevate the temperature of the whole surface being treat simultaneously. This is carried out by scattering light from the optical fibers. The fibers used for transmitting and diffusing the laser light are generally known as induced interstitial thermotherapy (ITT) fibers.
ITT fibers are well known. An example of an optical device which uses ITT fibers is described in U.S. Pat. No. 5,449,354 which discloses a device for treating the interior of a body cavity with laser energy particularly useful for the procedure. The described apparatus comprises at least two optical fibers each having a distal end adapted to be inserted into the body cavity to be treated, and a proximal end to be located externally of the body cavity and to be coupled to a source of laser energy. One of the optical fibers is axially movable with respect to the other optical fiber to either a retracted, non-operative position or to an extended, operative position. The distal ends of the two optical fibers are mechanically coupled together such that movement of one optical fiber axially with respect to the other causes the distal ends of the two optical fibers to spread apart laterally, and to direct the laser energy outwardly of the optical fibers.
In the preferred embodiment described in that patent, the optical fibers are disposed within a cannula having a distal end adapted to be inserted into the body cavity to be treated, and a proximal end to be located externally of the body cavity when the distal end is inserted therein. In the described device, there were three optical fibers within the cannula arranged in side-by-side relation, with two of the fibers being outer fibers, and the third fiber being the middle fiber straddled on opposite sides by the two outer fibers. The two outer fibers are axially movable with respect to the middle fiber; and the distal ends of the three fibers are mechanically coupled together such that movement of the two outer fibers axially with respect to the middle fiber causes the distal ends of all three fibers to spread apart laterally.
As described in U.S. Pat. No. 5,449,354, such a laser device is particularly useful for treating chronic menorrhagia since a single dosage of laser energy will substantially cover most or all of the uterine lining. Thus, the device avoids the need for the physician to view the interior of the uterus, and thereby the need for inserting a hysteroscope into the uterus. In addition, it reduces, or perhaps may even eliminate, the dilation required of the uterus, and also substantially reduces the time of treatment. Local anesthesia can be used and the procedure can be carried out with minimal training at lower risk to the patient.
U.S. Pat. No. 5,733,279 discloses a further device for treating the interior of a body cavity with laser energy without the need for a cannula, thereby reducing the dilation required of the uterus during treatment. The apparatus describes a device having at least two outer fibers and a middle fiber, in side-by-side relation each having a distal end to be inserted into the body cavity to be treated, and a proximal end to be located externally of the body cavity and to be coupled to a source of laser energy; and actuator means coupled to the optical fibers. In the preferred embodiment described in that patent, the actuator means comprises rods for coupling each of the outer fibers to the middle fiber, one end of the rods is pivotally connected to each of the distal ends of the outer fibers and the other end is pivotally connected to the middle fiber. This arrangement allows for manually activating the proximal end of the outer fibers to move axially with respect to the middle fiber so that the distal ends of the fibers spread.
Some of the prior art designs are not heat-durable and it is very difficult to control the intensity of the light being diffused.